Method of making sodium sulfate.



in. 870,746. IATBNIBD .Nov. 12, 1907 J. D. PENNOGK.

METHOD OF MAKING SODIUM SULFATE, APPLICATION Mum MAY 25. ms,

WITNESSES INVEN T00 Jofinfl. Pennoo/t QM MW I A rzanrm'.

UNITED STATES PATENT OFFICE.

J OHN D.PENNOGK, OF SYRACUSE, NEW YORK, ASSIGNOR-TO THE SOLVAY PROCESS COMPANY, A CORPORATION OF NEW YORK.

METHOD OF MAKING SODIUM. SULFATE.

Specification of Letters Patent.

Patented Nov. 12, 1907.

Application filed May 25. 1906. Serial No. 318.604-

To all whom it may concern:

Be it known that I, JOHN D. Pnnuocx, a citizen of the United States, residing at Syracuse, in the county of Onondaga and State of New York, have invented a new and useful Method of Making Sodium Sulfate, ,of which the following is a specification.

This invention relates to the manufacture of sodium sulfate.

The object of the invention is to providenn economical and effective method of converting commercial niter cake, or,acid sodium sulfate, I-INaSO,, into sodium sulfate. As is well known, acid sodium sulfate is produced in large quantities in the form of niter cake in the manufacture of nitric acid and is at the present time substantially a waste product. It has heretofore been proposed to convert this into sodium sulfate by various methods, none of which have proven sufiiciently advantageous to insure general adoption.

According to this process the niter cake, commonly containing the equivalent of about 36 percent. of free sulfuric acid, is mixed with a suitable sodium com-. pound having an alkaline reaction, as sodium hydrate or carbonate, or with a mixture containing the same. The alkaline sodium compound should be used in substantially the theoretical proportion required to neutralize the sulfuric acid present, and the mixture should be intimate, this being preferably effected by grinding the materials together. The mixture soprepared is then heated to bring about the reaction, the most effective temperature for rapid and complete reaction being from 250 to 300 C. This heating is preferably accomplished in a rotary cylinder heated internally by gas. I

I prefer to proceed substantially as follows:Commercial niter "cake containing about 90 percent. of

' acid sodium sulfate and 9 percent. of normal sodium sulfate is intimately mixed or ground with sodaash, the proportions being approximately 1000 pounds niter cake to 308 pounds soda ash. The resulting intimate mixture isfurnaced at a temperature of about 300 O. or somewhat less. In case small lumps are produced in the heating these may be afterward ground to powder.

The drawing represents in part section and part elevation, a device suitable for treating the materials in accordance with my method.

In this drawing 5 and 6 indicate hoppers for containing the materials to be treated, such for instance, .as .niter; cake and fished salts. These materials are fed or discharged by the screws 7 and 8 respectively, through conductors 9 and 10 respectively, to the grinding and mixing mill 11. From the grindingand mixing mill 11 the material thoroughly mixed passes through conductor 12 to the inclined rotary furnace 13 of usual form. This furnace is heated by a gas flame from pipe 14. The material after being subjected to the required temperature is discharged from the furnace at 15. I

' Instead of soda ash as above described I may use for neutralizing the acid sulfate the product known in the art as fished salts and consisting substantially of a hydrated mixture oi sodium hydroxid, carbonate and sulfate in proportions approximately as shown by the following analysis:

H O 18.75% NaOH 1168 N m, 46.21 Na SO,. .Q 18.87 NaCl .46

What I claim is:

1. The method of making sodium sulfate, whichconsists iii-mixing niter cnke'and a sodipm compound having an alkaline reaction, in approximately reacting proportions,

and heating the mixture to efiect reaction, substantially as described. v

2. The method of making sodium sulfate, which consists in mixing'niter cake and a sodium compound having an alkaline reaction, in approximately reacting proportions, and healing the mixture to a temperature above 125 C. to sheet reaction, substantially as described.

3. The method of making sodiurnsuifate, which consists in grinding together niter cuke and a sodium compound having an alkaline reaction, in approximately reacting proportions, thereby producing an intimate reacting mixture, and then heating said mixture to eflect reaction, substantially as described.

4. The method of making sodium sulfate, which consists in mixing niter cake and fished salts from the manufacture of salt in approximately reacting proportions, and heating the mixture to eifect reaction, substantially as described.

- JOiiN D. PENNOFK Witnesses Rom". CROASDALE, Eueuun E. Youuo. 

